This invention mainly relates to an electrostatic separating apparatus which separates supplied substances containing sheet-like substances into conductive substances (conductors) and insulating substances (insulators) by using electrostatic force (namely, Coulomb's force) and corona discharge together.
Conventionally, disclosure has been made about this kind of electrostatic separating apparatus in a paper (Owada, Electric Selection, "Source and Material": Vol. 113, No. 12, pp. 920-923, 1997).
Such an electrostatic separating apparatus separates supplied substances (namely, substances to be separated) into conductive substances and insulating substances using electrostatic force and corona discharge together.
This electrostatic separating apparatus is basically provided with a roller type ground electrode and an opposite electrode having a corona electrode and an electrostatic charge electrode from a supply side of the substance, and further has a brush for removing the insulating substances attached to the ground electrode.
Meanwhile, another disclosure has been made about an electrostatic separating apparatus in which a steel belt conveyor is used as the ground electrode in Japanese Unexamined Patent Publication (JP-A) No. S50-60866.
In the above-mentioned electrostatic separating apparatus, the supplied substances are separated into the insulating substances and the conductive substances by using the electrostatic force and the corona discharge together.
Under this circumstance, separating efficiency is excessively reduced when the sheet-like substances are contained in the supplied substances.
More specifically, when the separation is carried out by the use of the electrostatic force and the corona discharge, the insulating substances are attached to the ground electrode by the electrostatic force in electrostatic field generated between the ground electrode and the opposite electrode.
In the meantime, the conductive substances are not attached to the ground electrode, and thereby, are separated from the insulating substances. This is because the conductive substances have the same potential as the ground electrode by contacting with the ground electrode.
In consequence, the supplied substances must be contacted with the ground electrode in the electrostatic field to perform the electrostatic separation.
Under such a circumstance, when the sheet-like substances are contained in the supplied substances, the sheet-like substances prevent the conductive substances from contacting with the ground electrode. Consequently, the separating efficiency is remarkably reduced.
In addition, when the sheet-like substances contain a plurality of insulating substances, the sheet-like substances are strongly attached to a surface of the ground electrode because a surface area thereof is large. As a result, the sheet-like substances can not be removed by the brush provided in the conventional electrostatic separating apparatus.
When the sheet-like substances are left or remained on the condition that the substances are attached to the ground electrode, they are prevented the conductive substances in successively supplied substances from contacting with the ground electrode. Further, attaching force for the insulating substances is weakened. In consequence, the separating efficiency is remarkably reduced.
Thus, it is difficult to electrostatically separate the supplied substances containing the sheet-like substances in the conventional electrostatic separating apparatus.